CLINICAL RELEVANCE: The tear break-up time (BUT) test is important in diagnosing and monitoring tear film stability, and understanding potential changes in tear film dynamics during repeated measurements could improve the accuracy and reliability of the test in clinical practice. BACKGROUND: The study aimed to examine the changes in BUT value caused by subsequent measurements made in BUT test. METHODS: A total of 120 female participants were divided into groups (30 individuals each). Participants were divided into four groups based on the interval between two non-invasive tear break-up time (NI-BUT) tests: Group 1 (1-minute interval), Group 5 (5-minute interval), Group 10 (10-minute interval), and Group 15 (15-minute interval). The first NI-BUT test was called Initial NI-BUT (NI-BUT RESULTS: Participant ages ranged from 18 to 36 years, with a mean of 25.1 ± 3.2 years. The mean values of BUT CONCLUSIONS: Subsequent measurements cause increased BUT values. The longer the interval between two measurements, the smaller the differences between the subsequent measurements. When performing the BUT test, a single measurement should be preferred if possible. If the clinician finds the results of a single measurement unsatisfactory and wishes to consider the average of multiple measurements, the interval between tests should be longer than 15 minutes.